The engine may develop a stalling and/or no start condition due to a failed crankshaft position sensor.Google+
Car Problem Reports
Mercedes-Benz SL55 AMG Engine Performance Problems Due to Crankshaft Position Sensor Failure
Mercedes-Benz SL55 AMG Problem
Average Mileage: 53,000 mi (50,000 mi - 56,000 mi)
Driving to california from las vegas the engine sudenly stops in the middle of the desert 165 miles from vegas.car had to be flatbeded 200 miles,for repair....bad crank position sensor,never had this type of diaster with other cars,
Visitor, 2004 Mercedes-Benz SL55 AMG, 50,000 mi
Limped to dealer (after multiple stalls and restarts - replaced sensor and now fine.